U.S. Pat. No. 4,145,532, and copending application Ser. No. 938,907, filed Sept. 1, 1978, disclose cellulose solutions and precipitated cellulose articles formed from a tertiary amine oxide solvent containing up to about 29% water. It is also disclosed that an organic co-solvent may be used in quantities up to about 25% by weight of the total solution as a less expensive diluent for the amine oxide as to lower the viscosity of the solution, if desired.
Copending application Ser. No. 938,906, filed Sept. 1, 1978, describes tertiary amine N-oxide solutions, with or without water, containing up to 20% of a compound which increase the pH of the solution. Examples of such compounds include primary, secondary and tertiary amines. The pH-adjusting compounds of said copending application are present in the initial stages of solution preparation to aid in dissolution of the cellulose but are not necessarily completely miscible with the components of the final solution and, in some cases, may not be retained completely in the final solution, whereas the co-solvents of the present invention are retained and are completely miscible with the components of the final solution. The amines employed in the present invention are not specifically disclosed in said copending application.
Creely et al, Journal of Polymer Science: Polymer Letters Ed., 16: 291-295 (1978), describe polyamine complexes with cellulose, including complexes prepared from diethylenetriamine, N-(2-aminoethyl)-1,3-propanediamine, triethylenetetramine and bis(2-aminopropyl) amine.
Turbak et al, A Critical Review of Cellulose Solvent Systems, ACS Symposium, Series 58, ACS Washington, D.C., 1977, pp. 12-24, report the use of methylamine as a co-solvent with DMSO to dissolve cellulose.